The major portion of the foreground emission at angular scales \(\gtrsim \) degree for \(\nu \lesssim \)  150 MHz consists of DGSE. Figure REF  shows the brightness temperature map of the DGSE at 408 MHz made by [1]}, [2]}. It is seen that the brightness temperature of this emission (plotted as the logarithm of temperatures in K) is brightest at the galactic plane. However, there are observations of excess synchrotron power on angular scales \(\sim \)  degrees at “colder" regions near the North Celestial Pole and South Galactic poles [3]}, [4]}, [5]}. The average brightness temperature is between a few 10s to 100s K. The frequency dependence of the DGSE brightness temperature is approximated as a power law of the form \(T(\nu )\propto \nu ^{-\alpha }\) . Thus, the temperature would be much higher at lower frequencies. Besides synchrotron radiation, free-free emission and a small amount of radio emission from radio haloes and relics also contribute to the diffuse foreground to some extent.
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